The separation of an aqueous phase from an oil phase, particularly of crude oil and oil products, can, in principle, be effected by means of physical, chemical or thermal methods. The latter two methods frequently entail the subsequent emergence of secondary contaminations in the form of an additional loading of the waste water with chemicals. On the other hand, thermal methods require large amounts of energy and therefore are likewise regarded as neither ecologically nor economically appropriate. In contrast thereto, physical methods represent an environmentally friendly alternative that is particularly important from the standpoint of increasingly stringent environmental requirements.
This method is, however, disadvantageous in that productivity of the method, that is to say a throughput rate amount per unit of time, is relatively low, resulting in a considerable amount of time being necessary for larger quantities of oil-water mixtures to be separated.
Document DE 102 41 518 A1 teaches of a method of the type in question for separating an intermittent secondary phase from an aqueous primary phase, in a first step water droplets of a predetermined controlled size being formed, which droplets are, in a second step, conducted on a multi-phase separator unit on which they coalesce, are directed into a sump trap, subsequent to which they are separated. The coalesced and separated water is collected in a water pocket from which it is drawn off. For further refining and separation, for example, it is possible to incorporate downstream a mechanical emulsifying breaker-stage as well as one or a plurality of hydrophobic membranes.